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SingTel says Optus to blame for nationwide outage


The parent company of Optus has broken its silence on last week’s nationwide blackout, denying responsibility for the communications wipe-out that alienated millions of Australians and put future government contracts under review.

Singtel, the Singaporean telecommunications conglomerate that owns Optus, said on Thursday a routine upgrade was not the cause of last Wednesday’s daylong outage that cut off internet and mobile access for about 10.2 million customers.

“We are aware that Optus experienced a network outage after the upgrade when a significant increase in [internet] addresses being propagated through their network triggered preset failsafes. However, the upgrade was not the root cause,” a Singtel spokesman said in a statement.

“From time to time, STiX [the Singtel internet Exchange] conducts software upgrades for its infrastructure.

“STiX had planned for a routine software upgrade on one of its routers at 1am Singapore Time on November 8, 2023 (4am AEDT), and as per usual practice, gave prior notice to all affected customers, including Optus and other telecom companies.

“During the upgrade, data traffic was routed to other points of presence on the STiX network and back into customers’ networks.

“The STiX upgrade was completed within 20 minutes and all its customers’ routers that were connected to it, including Optus’, were up and running.”

On Monday, Optus blamed the failure on changes to “routing information” following the upgrade.

“At around 4.05am Wednesday morning, the Optus network received changes to routing information from an international peering network (Singtel internet Exchange) following a routine software upgrade,” Optus said in a statement.

“There routing information changes propagated through multiple layers in our network and exceeded preset safety levels on key routers which could not handle these.”

The statement said the action resulted in routers disconnecting from the Optus IP Core network to protect themselves.

This resulted in a large scale effort to reconnect or reboot the routers physically, requiring “the dispatch of people across a number of sites in Australia”.

“This is why restoration was progressive over the afternoon,” Optus said.

On Thursday, Optus said SingTel’s statement did not contradict its own assessment of the root cause of the failure.

“We are making changes to our network to ensure it will not happen again,” a spokesman told NCA NewsWire.

“Singtel is supporting Optus as we learn from what has occurred and continue to work to improve the resilience of our network.”

Pressure is mounting on the embattled telecommunications giant following the blackout.

South Australian Premier Peter Malinauskas has threatened to pull multimillion-dollar contracts with the company and Optus CEO Kelly Mayer Rosmarin will face a Senate grilling tomorrow on what went wrong on Wednesday.

Joanna Swanson

Joanna Swanson is Europe correspondent at the Thomson Reuters Foundation based in Brussels covering politics, culture, business, climate change, society, economies and inclusive tech. With specific focus in breaking news, she has covered some of the world's most significant stories.